[ci-scan] MAUI0003 sharded CollectionView category blocks UI-test builds

## Summary
UI-test project builds fail across platform legs because MAUI0003 rejects CollectionView tests that use the umbrella sharded category directly.

## Build Information
- **Pipeline**: maui-pr-uitests
- **Build**: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1594249
- **Build ID**: 1594249
- **Branch**: main
- **First seen**: 2026-09-12
- **Occurrences**: 1 in last 10 builds

## Affected Legs
- Android UI-test project builds
- iOS and MacCatalyst UI-test project builds
- Windows UI-test project builds

## Error Message
```
2026-09-12T17:57:49.6283930Z /mnt/vss/_work/1/s/src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue35889.cs(17,14): error MAUI0003: Test method 'EmptyCollectionViewCollapsesAndExpandsWithItems' uses the sharded category 'CollectionView' directly; use `[ShardedTestCategory(UITestCategories.CollectionView, shard: ...)]` so both the umbrella and CI shard categories are registered [/mnt/vss/_work/1/s/src/Controls/tests/TestCases.Android.Tests/Controls.TestCases.Android.Tests.csproj]
```

## Investigation Context
The analyzer diagnostic occurs in 187 required failed-leaf logs spanning Android, iOS, MacCatalyst, and Windows UI-test project builds. Compilation fails before the affected UI tests can run.

Start at src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue35889.cs:17 and inspect the CollectionView category used by EmptyCollectionViewCollapsesAndExpandsWithItems. Check the related sharding test-category definitions and build the affected UI-test project; done means MAUI0003 no longer blocks the Android, iOS, MacCatalyst, and Windows UI-test builds.

Written by the indexing model from the issue text.